1. Field of the Invention
The present invention relates to a developing device for fabrication of a semiconductor device and its controlling method and, more particularly, to a developing device for fabrication of a semiconductor device and its controlling method by which by-products left on a wafer after development can be completely removed.
2. Background of the Related Art
In general, a semiconductor device is fabricated by a series of processes such as photolithography, chemical etching, depositions of thin layers and the like. Photolithography is the process of forming visible images on a wafer with photographically produced plates or masks.
Photolithography includes two steps: exposure of a photoresist on the wafer to light such as ultraviolet rays; and development of the exposed photoresist in which the latent image becomes visible.
FIG. 1 illustrates a conventional development step in the above-described photolithography. When placed on a spin chuck 2, a wafer W sticks fast to the upper surface of the spin chuck 2 with vacuum pressure supplied from the bottom of the spin chuck 2. Then, the wafer W is coated with an amount of developer and the spin chuck 2 is rotated to the left and right two or three times at a low speed so as to uniformly spread the developer onto the wafer W. A predetermined pattern is formed when the exposed area of the positive photoresist and the unexposed area of the negative photoresist react with the developer and are dissolved.
After a period of time, a rinse is spread onto the pattern in order to wash off (undesired by-products produced during the reaction of the photoresist and the developer. Then, development is completed by rotating the spin chuck 2 at a high speed so as to completely remove moisture on the wafer W by centrifugal force.
In the process as described above, development is accomplished with the pattern-formed surface of the wafer W facing upward, and the by-products on the wafer W being removed by centrifugal force caused by rotations at high speed. Therefore, it is impossible to completely remove all by-products left on the wafer, for example in the corners 3 of the hollowed areas on the patterned wafer W. Thus, by-products not removed by centrifugal force may cause deterioration of the wafer during subsequent chemical etching.